Add pytest OpenSSH transport with password
    
    The pytest_multihost transport does not provide password-based
    authentication for OpenSSH transport. The OpenSSH command line tool has
    no API to pass in a password securely.
    
    The patch implements a custom transport that uses sshpass hack. It is
    not recommended for production but good enough for testing.
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>